Asphalt paving machine



Sept. 19, 1961 T. B. CRANE ETAL 3,000,277

ASPHALT PAVING MACHINE Filed Jan. 15, 1957 6 Sheets-Sheet 1 INVE TOR5 7260/4/25 B, fdrle, //dY/a// 7, iZZ6/ q,

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Sept. 19, 1961 T. B. CRANE ETAL 3,000,277

ASPHALT PAVING MACHINE Filed Jan. 15, 1957 6 Sheets-Sheet 2 INVENTORs, 7%60/1/6 ,5, C F4176, Harald 7. 2%/)6/y.

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T. B. CRANE ET AL ASPHALT PAVING MACHINE Sept. 19, 1961 6 Sheets-Sheet 3 Filed Jan. 15, 1957 Sept. 19, 1961 T. B. CRANE ETAL 3,000,277

ASPHALT PAVING MACHINE Filed Jan. 15, 1957 6 Sheets-Sheet 4 M EE-E- INVENTORS 72642 2,? :B. r

Scfea 1 Up Sept. 19, 1961 T. B. CRANE ETAL ASPHALT PAVING MACHINE 6 Sheets-Sheet 5 Filed Jan. 15, 1957 Sept. 19, 1961 'r. B. CRANE ETAL ASPHALT PAVING momma 6 Sheets-Sheet 6 Filed Jan. 15, 1957 mwmk Na i United States Patent Theodore B. Crane, 18211 Stansbury, Detroit, Mich., and

Harold F. Fehlberg, Detroit, Mich.; said Fehlberg assignor to said Crane Filed Jan. 15, 1957, Ser. No. 634,264

1 Claim. (Cl. 9445) This invention relates to asphalt paving machines, and more particularly to devices for spreading and screeding asphaltic paving materials preparatory to compressing the material with a roller.

Conventional asphalt pavers are adapted to move along a roadway or other area to be paved behind a truck containing a load of asphalt. The paver pushes the truck during the actual paving operation, the asphalt being discharged from the truck into a hopper mounted on the front of the paver and being spread from this hopper in a rough or general way. The conventional paver is provided with an agitator cylinder extending transversely to the direction of movement of the paver, this cylinder having projections which serve to agitate the layer of asphalt leaving the hopper so as to level off the layer. A screed is positioned behind the agitator cylinder, the screed comprising a transversely extending bar with a downwardly and rearwardly inclined lower surface which slides over the top of the layer, thus compressing it to the proper thickness. Conventionally, the screed is vertically adjustable by means of lead screws at its opposite ends. One operator is required to operate the machine and one or sometimes more helpers are stationed at a hand wheel mounted on each lead screw to adjust the screed as the paver advances.

It is an object of the present invention to provide a novel and improved asphalt paver which overcomes many of the deficiencies of conventional paving machines, and in which a single operator may easily perform all the necessary functions required for operation of the machine, eliminating the necessity for additional operators to control the screed height.

It is another object to provide an improved asphalt paver of the above character, which includes means for leveling the spread asphalt to a primary thickness immediately after it is released from the hopper, and in which the height and angularity of this primary leveling means may be automatically coordinated with that of the screed, so that a completely uniform layer may be produced despite required changes during advancement of the paver.

It is a further object to provide an improved paving machine of the above nature, which permits adjustment of the leveling elements while the paver is in motion, thus avoiding the creation of abrupt steps in the asphalt surface, and in which this operation may be performed by a single operator.

It is also an object to provide an improved asphalt paver of this nature which includes means for controlling the direction of movement of the paver by a guide wire mounted along the roadway, thus permitting the operator to devote his full attention to other operating parts of the machine while the asphalt is being paved.

It is a further object to provide an improved asphalt paver of this type in which the speed and direction of rotation of the agitator cylinder may be selectively controlled, thereby enabling the apparatus to be used most effectively with different grades of paving material as well as for base layers of crushed rock, gravel or the like.

It is another object to provide an asphalt paving machine of this character which carries the hopper as an integral part of the machine, and which nevertheless is extremely compact and may be easily constructed so as 2 to be within the maximum permissible size for transportation on streets and highways.

It is also an object to provide an improved asphalt paving machine of this nature which includes a screed of improved construction permitting higher and more evenly distributed heating, and which results in a greatly improved ironing or compressing effect.

It is also an object to provide an improved asphalt paving machine of this type having electrical controls compactly arranged at a single location, and in which the operator may conveniently mount these controls at either side of the machine.

Other objects, features and advantages of the present invention will become apparent from the subsequent description, taken in conjunction with the accompanying drawings.

In the drawings:

FIGURE 1 is a perspective view of the improved asphalt paving machine of this invention, showing the general relationship of the parts at the forward end of the machine;

FIGURE 2 is a front end elevational view of the machine, taken in the direction of the arrow 2 in FIG- URE 1 showing the construction of the pusher rolls and hopper;

FIGURE 3 is a rear elevational view of the machine taken in the direction of the arrow 3 of FIGURE 1 and showing the screed assembly;

FIGURE 4 is a side elevational view of the paver, parts being broken away, showing the agitator cylinder drive and the manner in which the machine is readied for transport;

FIGURE 5 is a fragmentary rear elevational view taken in the direction of the arrow 5 of FIGURE 4 and showing the construction of the screed supporting plate and associated parts;

FIGURE 6 is a top plan view of the construction shown in FIGURE 5, taken along the line 6-6 of FIGURE 5 with parts removed and indicating the manner in which the screed supporting plate is guided for vertical movement;

FIGURE 7 is a fragmentary elevational view of the primary cut-off plate and its guiding and adjusting means, taken along the line 7-7 of FIGURE 4;

FIGURE 8 is a top plan view of the parts shown in FIGURE 7;

FIGURE 9 is a fragmentary elevational view taken in the direction of the arrow 9 of FIGURE 1 and showing the box which contains the guide wire control switches;

FIGURE 10 is a fragmentary cross-sectional view in elevation taken along the line 10--10 of FIGURE 9 and showing the guide wire engaging lever;

FIGURE 11 is a fragmentary plan view of a portion of the reciprocating screed;

FIGURE 12 is a cross-sectional view in elevation taken along the line 12-12 of FIGURE 11 and showing the manner in which the flame nozzle is connected to the screed;

FIGURE 13 is a schematic view showing the connections between the engine and the power-driven portions of the machine;

a truck which carries the asphalt. A hopper at the forward end of the machine is adapted to receive material from the trucleand spread this material beneath. the frame and between the endless tracks. A primary cut-off plate in the form of a transversely extending blade is positioned behind the hopper and serves to roughly grade the material as it leaves the hopper. Therear portion of the machine carries a rotatable agitator cylinder to further increase the uniformity of spreading. A screed is mounted behind. the agitator cylinder for horizontal transverse reciprocation, the screed comprising a bar having downwardly and rearwardly inclined surfaces which compress the asphalt to its properthickness as the machine advances, preparatory for the rolling operation. Means are. provided for applying heat along the length of the screed to further increase its effectiveness.

Power-operated means are provided for adjusting the size of opening in the bottom of the hopper, the height and transverse angularity of the primary cut-off plate and screed, and the. direction and speed of rotation of the agitator cylinder. Further control means are included which permit simultaneous adjustment of the primary cut-off plate and screed so that all portions of the screed Will operate with equal effectiveness at all times. Controls are also provided for steering the paver by means of selective braking of theendl'ess tracks. A guide wirecontrolled switching mechanism may be utilized for this purpose if desired, the vehicle being steering in accordance with its position relative to a wire mounted alongside the surface to be paved. All the electrical controls are located on a single box which may be mounted adjacent either side of the machine, so that the operator may view the 'paving operation from the most advantageous position. The'pusher rolls, the forward portion of the hopper, and the screed heating connections are removably mounted, and the parts of the mechanism are so arranged that the assembly may easily be placed in readiness for transport on roads or highways and may be so constructed that, when loaded sideways on a trailer,.its width will be below the maximum permissible size for road transport, normally about eight feet in most States..

Referring more particularly to the. drawings, the paving machine is generally indicated at 21 and comprises a main frame 22 partially visible in FIGURES l, 2 and 4. This frame is supported at its opposite sides by a pair of endlesstraeks 23 and '24 which are drivable by. aninternal-combustionI engine 25 mounted above a platform 26 on the frame 22. The means through which engine 25 drives tracks 23 and 24 will be described later with .relation to the schematic drive layout shown in FIGURE 13. Steering of machine 21 to the right or left is accomplished by selective braking of tracks 23 and 24, this braking beingcontrolled by a pair of solenoids which control.the brakes for tracks 23 and 24. The details of the brake itself are conventional and need not be described in detail; the solenoids are shown in the circuit diagram of FIGURE 14, with respect to which the manual and automatic controls for these solenoids will be later described. It should be noted that engine 25 is mounted to one side of plateform 26, as seen in FIGURE 1, and has its longer axis extending transversely to the direction of movement of machine 21, thus affording an extremely .compact arrangement in conjunction with the other portions of the machine. 7

Disposed forwardly from main frame22 on a pair of axles 27 and 28 are two pusher rolls 29 and 31 respectively, these rolls being best seen in FIGURES 1 and 2.

Rolls 29 and 31 are adapted toengage the rear tires of a truck (not shown) loaded with asphalt, and for this purpose the axles are suported forwardly of machine 21 .by bars 32 and 3.3 which are telescopically. mounted with- .in sleeves 34 and 35 supported at .the forward end of ma n f a e 2 -v n pa lar; as seen be t in GUR .2,. .e es 4. t nd 35 ar te e copic y. .rn u t d fixed sleeves 36 on main frame 22 by meansof bolts" 37.

A plurality of apertures 38 are provided in sleeves 34 and 35 so that these may be secured in adjusted position within sleeves 36. Stops (not shown) are disposed within sleeves 34 and 35 so that rolls 29 and 31 will be held in position. v t

Mounted at the forward portion of machine 21 above pusher rolls 29 and 31 is a hopper generally indicated at 39 for receiving the asphalt from the truck. Hopper 39 has a transverse bacl; plate 41 and side plates 42 which converge downwardly toward the hopper bottom. The forward end of hopper 39 carries an extension 43 having side sections 44 securable to the forward edges of side walls 42, as best seen in FIGURES 1 and 2. As shown in FIGURE 4, hopper extension 43 and pusher rolls 29 and 31 when assembled occupy the positions shown in dot-dash lines. When these parts are disassembled from the remainder of machine 21, the total front-to-rear size of the machinewill be considerably decreased. As will appear from the following description, the remaining size may be such that, when machine 21 is loaded sideways on a transport trailer, it will be within the permissible maximum size for transportation on roads and streets.

As best seen in FIGURE 4, the lower portion of hopper 39 is provided with a downwardly and rearwardly inclined plate 45 leading to the open hopper bottom. A horizontal sliding door 46 is mounted for adjustably selecting the rate at which the paving material falls from the hopper. Movement of door 46 is controlled by a pair of cylinders 47 and 48, cylinder 47 being indicated in FIGURE 4. These cylinders are connected adjacent opposite ends of door 46 and are hydraulically controlled, as described below with respect to FIGURE 15. Immediately behind the bottom of hopper 39 and the means connecting door 46 and cylinders 47 and 48 is a primary cut-off plate 49, the position of which is best seen in FIGURE 4. This plate comprises a transversely extending vertical blade which serves to level ofi the top of the spread asphalt as machine 21 advances. Raising and lowering of primary cut-off plate 49 is controlled by a pair of cylinders 51 and 52, cylinder 51 being indicated in FIGURE 4. These cylinders are connected to opposite ends of plate 49 and are individually controlled, as described below with respect to FIGURE 15, so that the angular slope as Well as the height of plate 49 may be selectively adjusted. The'rearward position of door 46 will of course be limited by plate 49.

The means for supportingand guiding cut-off plate 49 is shownin detail in FIGURES 7 and 8, these figures showing the construction adjacent cylinder 51. Secured to the inner surface of ajlongitudinal frame member 53 are a pair of vertical. guides 54 and 55 between which are disposed an edge of cut-off'plate 49. A similar constr-uction (not shown) is provided at the opposite end of the cut-off plate. Cylinder 51 has a piston rod 56 which is pivotally connected at its lower end 57 to the lower edge of cut-off plate49. Cylinders 51 and 52 are doubleacting cylinders, and it will be seen that actuation of either cylinder will cause vertical movement of the corresponding end of plate 49. Itwill be noted, on examination of FIGURES 7 and 8, that a substantial space 58 is provided between the edges of'plate" 49 and frame members 53. Thus, substantial tilting of plate" 49 in a lateral direction may occur'without interference with the stationary portions of the machine.

The rear portionlof machine 21 is provided with a pair of side plates 59 and 61,"best seen in FIGURES 1, 3 and 4. An agitator cylinder 62 is rotatably supported bea plurality of teeth 6 5 on its outer surface, the positions and shape of these teeth being such that when cylinder62 is rotated in a counter-clockwise direction in FIGURE 4 the layer of asphalt which has been roughly graded by primary cut'off plate 49 will be agitated so as to loosen or break up the particles and evenly spread the layer of material, thus preparing it for the screeding operation. Preferably, the tooth construction is also adapted to dress base layer material such as crushed rock, slag or gravel when cylinder 62 is rotated in the opposite direction.

The screed assembly is best seen in FIGURES 3, and 6 and comprises a screed supporting plate 66 extending transversely of the machine, the ends of plate 66 being guided for vertical movement between guide members 67 secured to plates 59 and 61 respectively. As in the case of primary cut-ofi plate 49, a substantial space 68 exists between the side edges of plates 66 and plates 59 and 61, thus permitting tilting movement of the screed supporting plate in addition to vertical movement. The lower edge of plate 66 is provided with a plurality of spaced brackets 69 for supporting he screed in such a manner that it may reciprocate horizontally in a transverse direction with respect to the direction of movement of machine 21, as will be described below.

The screed is generally indicated at 71, and its construction is best seen in FIGURES 5, 6, 11 and 12. As stated previously, the purpose of the screed is to cornpress or iron down the asphalt layer preparatory for the rolling operation. For this purpose, screed 71 is provided with an elongated metal bar 72 having a plurality of forwardly projecting teeth 73. Bar 72 is preferably constructed of a thick piece of metal stock having high heat-retaining capacity. The lower surfaces 74 of teeth 73 are downwardly and rearwardly inclined, as is best seen in FIGURE 12, and flanks 75 of the teeth slope upwardly away from surfaces 74 in such a manner that when screed 71 is reciprocated, surfaces 75 will engage the asphalt layer with a downwardly compressing action. Secured to the upper and lower surfaces respectively of bar 72 are an upper plate 76 and a lower plate 77, these plates extending rearwardly from bar 72 and being joined by a vertically extending rear plate 78. Preferably, layers of insulation 79 and 81 are disposed along the inner surfaces of plates 76 and 77, so that heat will be imparted to bar 72 rather than these plates.

It will be noted that a chamber 82 is formed within screed 71, and this chamber is supplied with heat during the paving operation. In particular, a plurality of apertures 83 are provided in rear plate 78 into which flame nozzles 84 project, these nozzles being detachably supported on screed 71 by L-shaped brackets 85 secured to the nozzles. Nozzles 84 are supplied with fuel from one or more tanks 86 resting on platform 26, a conduit 87 leading from the desired tank to a header 88 to which nozzles 84 are secured. Conduit 87 is preferably flexible so that the header and its attached nozzles 84 may be detached from screed 71, thus further decreasing the overall length of machine 21 for transportation purposes. This relationship of the parts is shown most clearly inFIG- URE 4. A plurality of heat exit apertures 89 are also provided in rear plate 78 of screed 71, these apertures being alternately located with respect to apertures 83. In this manner, the most efiicient degree of hot air flow may be obtained within chamber 82, thus imparting the maximum amount of heat to screed bar 72.

The manner in which screed 71 is mounted on screed supporting plate 66 is shown best in FIGURES 5 and 6. A slide bar 91 is secured to screed 71 in spaced parallel relation above the screed, bar 91 being somewhat shorter than screed 71. The undersurfaces of brackets 69 are provided with fingers 92 slidably supporting bar 91 so as to permit horizontal reciprocation of the screed. The means for actuating screed 71 comprises a double-acting cylinder 93, best visible in FIGURE 3, which is connected to an upstanding bracket 94 on bar 91 by a piston rod 95. Although the manner in which cylinder 93 is actuated will be described in detail below, it should be noted with respect to FIGURE 3 that a container 96 enclosing limit switches is secured to screed supporting plate 66, the switches being actuated in response to the movement of piston rod through a switch actuating bar 97. [All electrical cable 98 is connected between container 96 and the control system for the machine.

Means are provided for vertically reciprocating or angularly tilting screed supporting plate 66 together with screed 71. For this purpose, a pair of upstanding brackets 99 and 101 are secured to plates 59 and 61 respectively, as seen in FIGURE 3, and a horizontal supporting bar 102 extends between these brackets. As is seen best in FIG- URE 5, a pair of double-acting cylinders 103 and 104 are secured to the underside of bar 102 and project downwardly through annular clearance tubes 105 provided in supporting plate 66. Piston rods 106 project from cylinders 103 and 104 and are pivotaly connected to the lower portion of plate 66, so that vertical movement of either piston rod will raise or lower the corresponding end of plate 66 together with the screed. 'It should be noted that the diameter of clearance tubes 105 is sufficiently larger than that of cylinders 103 and 104 to permit tilting action of the screed supporting plate and screed without interference between the parts. Screed oscillating cylinder 93, being mounted on plate 66, may also operate uninterruptedly when the plate is tilted. Hydraulic conduits 107 and 108 are connected between the opposite ends of cylinders 103 and 104 and terminals 109 secured to bar 102. The latter bar is preferably hollow so that the hydraulic conduits may be connected to the remainder of the hydraulic system through this bar. Clearance slots 111 are provided in tubes 105 to facilitate the connection between conduits 107 and the lower ends of cylinders 103 and 104.

In order to center screed supporting plate 66 in a lateral direction, a pair of compression springs 112 are provided, one of these springs being visible in FIGURE 5. Each spring 112 is disposed between a piston 113 and the piston rod end of a cylinder 114 within which the piston is disposed. The head of each cylinder 114 is pivotally connected at 115 to the upper edge of screed supporting plate 66 adjacent one end thereof, and each piston rod 116 is pivotally connected at 117 to a central portion of stationary horizontal bar 102, as seen in FIGURE 3. Cylinders 114 are inclined upwardly toward the center of the machine, and it will be seen that the action of compression springs 112 will be such as to center screed sup porting plate 66 between stationary side plates 59 and 61. The strength of springs 112 is preferably such that plate 66 will be prevented from substantial horizontal movement due to reaction forces on cylinder 93 when screed 71 is oscillated. During vertical or tilting movement of plate 66, springs 112 will expand or contract while still maintaining plate 66 in a centered position.

The switch mechanism by means of which machine 21 may be guided by a wire stretched alongside the roadway is best seen in FIGURES 1, 9 and 10. This mechanism comprises a switch container 118 removably mounted on a longitudinal frame member 119 adjacent endless track 24. A lever 121 is pivoted within the container and has a downwardly projecting portion 122 spaced laterally outwardly from frame member 119. The lower end of portion 122 is forked as shown at 123 to receive a wire 124 stretched alongside the roadway a few inches off the ground. The pivot axis of lever 121 is parallel to the longitudinal axis of machine 21, and it will therefore be seen that as machine 21 approaches or recedes from wire 124, lever 121 will be swung around its pivot axis. The manner in which the resulting switch action will control the brakes for tracks 23 and 24 is described in detail with respect to FIGURE 14. Container 118 is capable of being mounted adjacent track 25 instead of track 24 so that wire 124 may be stretched on either side of the road.

Means are provided for permitting the operator to sit on either the left or right side of machine 21, and for this purpose the machine is provided with a detachable seat 125 which may be secured to either of two brackets 126 and 127 on the left and right hand sides of the machine respectively, as seen in FIGURE 3. A control box 128, best seen in FIGURES 3 and 4, is provided with the necessary switches which are shown schematically in FIGURE 14. Control box .128 is provided with a downwardly projecting sleeve 129 within which an electrical terminal is disposed. A pair of mounting posts 131 and 132 are provided at the left and right operators stations respectively, the upper ends of these posts having corresponding terminals, so that either terminal may receive the terminal in box 128 when sleeve 129 is placed on a post. In this manner, it will be seen that the operators station may be conveniently shifted merely by fastening seat 125 to the appropriate bracket 126 or 127, and slipping box 128 on the corresponding post 131 or 132. The clutch, change speed and reversing levers, shown schematically in FIGURE 13, are disposed in the central area of machine 21 so as to be accessible from either operators station. 'In order to readily ascertain the height of primary cut-oft plate 49, a gauge 133, visible in FIGURE 3, is secured to plate 49 and extends upwardly so as to be visible by the operator. A similar gauge 134 may be secured to screed supporting plate 66. A spirit level 135, likewise visible in FIGURE 3, is preferably secured to the upper edge of plate 66 in order that the angularity of screed 71 may be determined. A similar gauge (not shown) may be provided for cut-ofi plate 49. Appropriate pressure and temperature gauges for the hydraulic system and the screed may likewise be provided.

The driving connections between engine 25 and the power-actuated elements of machine 21 are shown schematically in FIGURE 13. Engine 25 drives a shaft 136 which is connected to a shaft 137 through a clutch 138. A handle 139 is provided for engaging and disengaging clutch 138. Shaft 137 drives a transmission 141 controlled by a handle 142, this transmission having a plurality of forward speeds and a reverse position. Transmission 141 drives a shaft 143 which is connected to a track drive transmission 144 controlled by a handle 145. Transmission 144 is shiftable to either a forward or reverse position, and has an output shaft 146 which drives a countershaft 147 connected to endless tracks 23 and 24.

Transmission 141 also has an output shaft 148 which drives a transmission 149 controlled by a lever 151. Transmission 149 is connected by shaft 64 to agitator cylinder 62 through the chain and sprocket connection mentioned previously. Transmission 149 also operates a power take-off unit 152 controlled by a clutch 153, this power take-off unit driving a pump 154 through a chain-and-sprocket connection .155. Pump 154 supplies the hydraulic pressure for the cylinders which operate the track brakes, primary cut-01f plate 49, screed supporting plate 66, hopper door cylinders 47 and 48, and screed oscillating cylinder 93.

FIGURE shows the system by means of which the hydraulically actuated portions of the mechanism are operated. Pump 154 is supplied by a tank 155, a pressure relief valve 156 and a gauge 157 being provided between the pump and tank. The cylinders for operating the left and right track brakes are designated at 158 and 159 respectively. These cylinders are of a single-acting type and when pressurized act to apply their corresponding brake (not shown), the brakes being released when the cylinders are de-energized by springs 160. Cylinders 158 and 159 are controlled by three-way valves 161 and 162 respectively, each valve being movable between a brake-releasing position shown in FIGURE 15 and a brake-applying position. When in brake-releasing position each valve 161 or 162 will connect its corresponding cylinder to tank conduit 163. The valves are controlled by solenoids 164 and 165 respectively, and when either solenoid is energized, its corresponding valve will be shifted leftwardly to its brake-applying position, causing supply conduit 1 66 to-be. connected to the corresponding cylinder. It will be noted that each brake cylinder 158 and 159 may be independently controlled, so that a high degree of maneuverability is afforded for machine 21.

Hopper door actuating cylinders 47 and 48 are simultaneously controllable by a valve 167 which is movable from a neutral position shown in FIGURE 15, in either direction by solenoids 168 or .169. Cylinders 47 and 48 are of a double-acting type, and when valve 167 is in its neutral position, fluid will be locked in these cylinders, thus holding hopper door 46 in its adjusted position. Upon energization of solenoid 168, valve 167 will be moved to the right in FIGURE 15, connecting supply conduit 166 with cylinder conduit 171 and tank conduit 163 with cylinder conduit 172 to cause outward movement of the cylinder pistons, thus moving door 46 toward its closed position (to the left in FIGURE 4). When solenoid 169 is energized, valve 167 will be moved to the left, causing retraction of the pistons and opening movement of door 46, with supply conduit 166 con nected to conduit .172 and tank conduit 163 to conduit 171.

Cylinders 51 and 52 for adjusting primary cut-01f plate 49 are independently controlled by valves 173 and 174 respectively. These valves are of similar construction, each valve being controlled by a pair of solenoids. The solenoids for valve 173 are designated as 175 and 176, while those for valve 174 are marked 177 and 178. As will be noted later with respect to FIGURE 14, each of these four solenoids may be independently controlled, so that primary cut-off plate 49 may be raised, lowered or tilted in any desired manner. For instance, the upper end of cylinder 51, as seen in FIGURE 15, may be pressurized by energization of solenoid 175, while the lower end is connected to tank. Assuming that cylinder 51 controls movement of the left side of primary cut-off plate 49, pressurization of the upper end of this cylinder will cause lowering of the left side of plate 49, since the piston of cylinder 51 will be extended. Reverse operation of cylinder 51, and operation of cylinder 52, will be obvious from the above example.

Cylinders 103 and 104 which control movement of screed supporting plate 66 are likewise controlled by two independent valves, these being designated as 179 and 181 in the figures. Valve 179 is controlled by a pair of solenoids 182 and 183, while valve 181 is controlled by solenoids 184 and 185. Like valves 167, 173 and 174, valves 179 and 181 are movable from a neutral position as shown in FIGURE 15 in either direction by energization of their appropriate solenoids. Raising, lowering and tilting movement of screed 71 may thus be readily controlled by solenoid energization.

The oscillating movement of screed 71 is obtained by cylinder 93 which is controlled by a valve .186 similar to valves 167, 173, 174, 179 and 181. Cylinder 93 is of a double-acting type, and valve 186 is movable between the position shown in FIGURE 15 and a position to the right of this position. Valve 186 is controlled by a pair of solenoids 187 and 188 which in turn are energized in response to the movement of the limit switches contained in box 118. When solenoid .187 is energized, valve 186 will be moved to the right, causing supply conduit 166 to be connected to conduit 189, thus causing rightward movement of the piston within cylinder 93. With solenoid 188 energized, supply conduit 166 will be connected to conduit 191, thus causing leftward movement of the piston. In order to permit operation of the paving machine without oscillation of screed 71, both solenoids 187 and 188 may be deactivated by a manual on-ofi switch 190, shown in FIGURE 14.

Preferably, speed control valves 192 are disposed in the lines leading to cylinders 47, 48, 51, 52, 103, 104 and '93. These valves permit unrestricted fluid flow toward their respective cylinders, but are adjustable so as to selectively restrict fluid flow away from the cylinders. In this manner, the rate of movement of hopper door 46, primary cut-off plate 49, screed supporting plate 66 and screed 71 may be controlled to suit individual requirements.

FIGURE 14 shows a suitable electrical control system for operating the solenoids described with respect to FIG- URE 15. A source of power such as a battery 193 is connected across lines 194 and 195 for supplying the electrical circuit. In general, the solenoids are controlled by normally open push button switches mounted on control box 128. Left steering solenoid 164 is provided with a push button switch 196, while right steering solenoid 165 has a switch 197. In parallel with these two normally open switches are a pair of conduits 198 and 199 respectively which may be selectively placed in series with either solenoid 164 or 165 by a reversing switch 201. Conduit 198 is in series with a normally open switch 202 while conduit 199 has a normally open switch 203. These two switches are enclosed within container 118 controlled by lever 121 which is actuated in response to its position relative to wire 124 stretched along the roadway. When lever 121 is in the neutral position shown in FIGURE 14, both switches 202 and 203 are open. Should arm 121 swing clockwise from its position shown in FIGURE 14, switch 202 will close, causing energization of left steering solenoid 164 or right steering solenoid 165, depending on the position of reversing switch 201. Likewise, counterclockwise movement of arm 121 will energize the other solenoid. In this manner, automatic steering may be accomplished with container 118 mounted on either side of the paving machine.

Hopper door closing solenoid 168 is in series with a normally open push button switch 204, while hopper door opening solenoid 169 is provided with a switch 205, so that the position of the hopper door may be easily controlled. A normally open push button switch 206 is provided, this switch having two poles in series with solenoids 176 and 177 respectively. When this push button switch is depressed, both ends of the primary cut-oii plate will be lifted. For lowering the cut-off plate a switch 207 is provided, this switch likewise being of double pole construction and in series with solenoids 175 and 178.

Means are provided for causing simultaneous coordinated tilting movement of the primary cut-oft plate and screed supporting plate in either direction. For this purpose, a normally open double pole push button switch 208 is provided in series with solenoids 176 and 183. Actuation of this push button switch will cause the left ends of the cutofi plate and screed supporting plate to be lifted while the right ends remain stationary. A similar switch 209 is connected in series with solenoids 175 and 182, actuation of this switch causing downward movement of the left ends of the primary cut-off plate and screed supporting plate. A switch 211 in series with solenoids 177 and 184 will, when actuated, cause upward movement of the right ends of the cut-off and screed supporting plates, the left end remaining stationary. Lastly, a switch 212, in series with solenoids 178 and 185 will cause downward movement of the right ends of these plates. It will thus be seen that, should it be necessary to change the crown or pitch of the grade, this may be easily done without decreasing the efliciency of operationof the unit.

In order to raise both ends of the screed supporting plate simultaneously, a normally open double pole push button switch 213 is provided in series with solenoids 182 and 185. Downward movement of the screed will be controlled by a similar push button switch 214 in series with solenoids 183 and 184. The primary cut-off plate and screed may thus be raised and lowered independently of each other and, if desired, may be simultaneously tilted in either direction.

Limit switch 96 for control of screed oscillation is a single pole-double throw switch which will be in series 10 with either solenoid 187 or 188, depending upon the position of limit switch actuating shaft 97. As shown schematically in FIGURE 14, a lost motion connection is provided between shaft 97 and switch 96 so that solenoids 187 and 188 will be alternately energized as the screed reaches the end of each stroke. Normal on-off switch 190 in series with switch 96 will enable both solenoids to be deactivated in order to halt screed oscillation.

Operation Assuming that machine 21 has been transported to the construction site, the machine will initially be in the condition shown in solid lines in FIGURE 4. When in this condition, the length of the machine will be relatively short, so that it may be carried sideways on a road trailer. After being unloaded from the trailer, sleeves 34 and 35 will be inserted in stationary mounting sleeves 36, bolts 37 being inserted in the proper apertures 38 in accordance with the desired position of the pusher rolls. Mounting bars 32 and 33 of pusher rolls 29 and 31 will next be inserted in sleeves 34 and 35 respectively in readiness for engagement with the rear wheels of the asphalt truck. The forward portions 43 and 44 of hopper 39 are next mounted in position, as shown in dotdash lines in FIGURE 4. Flame nozzles 84 are inserted in apertures 83 of screed 71, these nozzles together with header 88 being supported on the screed by brackets 85. Operators seat and control box 128 are then mounted on either the left or right side of the machine, depending on where the operator is to be situated.

Flame nozzles 84 are ignited to heat screed bar 72, the heated air passing through screed chamber 82 and apertures 89. With engine 25 started, the paver is placed in position in back of the asphalt truck, hopper 39 loaded, and the parts of machine 21 brought to their adjusted positions. In particular, hopper door 46 is adjusted by means of cylinders 47 and 48 to the proper opening, and primary cut-ofi plate 49 as well as screed supporting plate 66 are raised or lowered until in their proper positions as indicated by scales 133 and 134 respectively. If the roadway is to be crowned or pitched, the proper angularity of the primary cut-off plate and screed are selected by actuation of the left or right cut-oil plate and screed supporting plate cylinders, the degree of tilt being indicated by level 135. Cylinder 93 will be pressurized and screed 71 will begin to reciprocate in :a transverse direction, alternately energizing solenoids 187 and 188 to shift valve 186 which controls the screed oscillating cylinder.

When the paving is to begin, track driving shaft 147 will be actuated by proper adjustment of handle and agitator cylinder 62 will be rotated by shifting of handle 151, as shown in FIGURE 13. The speed of rotation of cylinder 62 will be selected in accordance with the material being laid. Should the machine be used to spread base layer material such as crushed rock, cylinder 62 may be rotated in a reverse direction and the screed retracted. The asphalt will be delivered onto the ground from hopper 39, and will be roughly graded by primary cut-oif plate 49. As the machine advances, the asphalt will be agitated by cylinder 62, and will then be compressed by reciprocating and advancing screed 71.

During this operation, the operator sitting in seat 125 may watch the entire procedure and maintain full control of all elements of machine 21. In particular, the height and angularity of plates 49 and 66 will be ascertainable by means of scales 133 and 134 as Well as level 135. Hydraulic pressure will be known through gauge 157 and screed temperature may also be indicated by a conventional thermometric device (not shown).

Assuming that steering is being manually controlled, machine 21 may be steered to the left by pressing push button 196. This will cause energization of solenoid 164, shifting valve 161 and pressurizing cylinder 158 to apply the brake to track 23. Similarly, rightward steering may 11 be obtained by pressing .push button 197 to energize solenoid 165, thus pressuaizing right brake cylinder 159.

Should it be desired to further close hopper door 46, push button 204 will be pressed, energizing solenoid 168 to shift valve 167 to the right in FIGURE 15. This will connect conduit 17 1 to supply conduit '166, extending the pistons of cylinders 47 and 48. Should it be desired to open the hopper door, solenoid 169 will be energized by pressing push button 205, thus pressurizing the opposite ends of cylinders 47 and 48.

To raise cut-off plate 49, push button 206 will be pressed, energizing solenoids 176 and 177. This Will cause leftward shifting of valve 173 in FIGURE 15 and rightward shifting of valve 177. The lower ends of cylinders 51 and 52 will thus be pressurized from supply conduit 166 through conduits 215 and 2116 respectively, raising both ends of cut-off plate 49. To lower the cutoff plate, push button 207 is pressed, energizing solenoids 175 and 178. Rightward shifting of valve 173 and leftward shifting of valve '174 will cause conduits 217 and 218 to be connected to supply conduit 166, while conduits 215 and 216 are connected to drain conduit 163.

In order to raise screed supporting plate 66 together with screed 71, push button 214 is pressed, energizing solenoids 183 and 184. This will cause leftward shifting of valve 179 and rightward shifting of valve 181 in FIG- URE 15, connecting the lower ends of cylinders 103 and 104 to supply conduit 166 through conduits 219 and 221 respectively. In order to lower the screed, push button 213 is pressed, whereby energization of solenoids 182 and 185 will cause valve 179 to shift to the right and valve 181 to shift to the left. Conduits 222 and 223 will thereby be pressurized from supply conduit 166, while conduits 219 and 221 are connected to tank conduit 163.

In order to lift the left ends of cut-off plate 49 and screed 7i, push button 208 is pressed, energizing solenoids 176 and 183. By fluid connections previously described, the pistons of cylinders 51 and 103 will be raised while the pistons of cylinders 52' and 104 remains stationary. Due to the nature of the hydraulic system as well as the availability of adjustable valves 192, the rate of movement of the cut-01f plate and screed cylinders may be adjusted so that their angularity may be changed at -a uniform rate. To lower the left ends of the cut-off plate and screed, push button 209 is pressed, energizing solenoids 175 and i182. The upper ends of cylinders 51 and 103 will thus be pressurized, causing downward movement of the left ends of the cut-off plate and screed. Upward and downward movement of the right ends of the cut-off plate and screed by actuation of push buttons a 2 11 and 212 will be obvious from the foregoing discuss1on.

Should it be desired to control steering of machine 21 automatically, wire 124 will be stretched along the edge of the roadway and engaged in the forked end 123 of lever 121. Reversing switch 201 will be closed in one direction or the other depending on which side of the paving machine container 118 is mounted, and as machine 21 advances switches 202 and 203 will be closed in response to changes in the lateral position of machine 21 with respect to wire 24. This will cause energization of solenoids 164 and 165 to steer machine 21 in a manner similar to that achieved by manual push buttons 196 and 197.

It will thus be seen that an extremely Versatile and eflicient asphalt paving machine is provided which requires a minimum of operating personnel and in which the paving elements may be closely controlled without manual exertion. The machine may be used on asphalt or other surfacing or base layer materials with a large range of thicknesses and pitches and under adverse temperature 12 and weather conditions. Due to its compact nature, the paving machine may be conveniently constructed so as to be within the permissible size for road transportation, with the parts being quickly and easily assembled in the field for use.

While it will be apparent that the preferred embodiment of the invention disclosed is well calculated to fulfill the objects above stated, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the subjoined claims.

What is claimed is:

In an asphalt paving machine, a frame having longitudinal frame members, a screed supporting plate extending transversely between said frame members, a screed carried by said plate, means for oscillating said screed, guide means on said frame members for permitting vertical movement of said plate, the length of said plate being shorter than the space between said frame members, a frame member extending transversely between said longitudinal frame members above said plate, a pair of springs connected between a central portion of said transverse frame member and opposite ends of said plate exerting equal and opposite forces on said plate and maintaining said plate in centered position between said longitudinal frame members, the strength of said spring means being such that substantial horizontal movement of said plate due to reaction forces from said oscillating screed will be prevented, a pair of vertically disposed cylinders secured to the underside of said transverse frame member at opposite ends thereof, a pair of clearance tubes formed in said plate for receiving said vertical cylinders, the internal diameter of said clearance tubes being substantially larger than the diameters of said vertical cylinders, and pivotal connections between the piston rods of said vertical cylinders and said plate, whereby tilting movement of said plate with respect to said frame will be permitted.

References Cited in the file of this patent UNITED STATES PATENTS 1,281,428 Stout Oct. 15, 1918 1,504,679 Dietz Aug. 12, 1924 1,509,236 Greene Sept. 23, 192A- 1,819,866 Cameron June 7, 1929 1,840,970 Noble Jan. 12, 1932 2,086,469 Bullard July 6, 1937 2,092,458 Krout Sept. 7, 1937 2,168,507 Barber Aug. 8, 1939 2,185,645 Mosel Jan 2, 1940 2,225,481 Lundbye Dec. 17, 1940 2,273,254 Davis Feb. 17, 1942 2,303,812 Barber Dec. 1, 1942 2,380,435 Heltzel July 31, 1945 2,393,954 Baker Feb. 5, 1946 2,601,277 Green Jan 24, 1952 2,589,256 Homing Mar. 18, 1952 2,591,502 Bohannan Apr. 1, 1952 2,641,975 Cletus et al June 16, 1953 2,663,231 Wood Dec. 22, 1953 2,669,915 McConnaughay Feb. 23, 1954 2,777,221 Ciabattoni Jan. 15, 1957 2,791,412 Hatcher May 7, 1957 2,797,763 Blesener July 2, 1957 FOREIGN PATENTS 1,095,178 France Dec. 15, 1954 514,341 Italy Feb. 9, 1955 OTHER REFERENCES Construction Methods and Equipment, January 1954, p. 121. 

